title: Extracellular laccase produced by an edible basidiomycetous mushroom, Grifola frondosa: purification and characterization.
abstract: A major laccase isozyme (Lac 1) was isolated from the culture fluid of an edible basidiomycetous mushroom, Grifola frondosa. Lac 1 was revealed to be a monomeric protein with a molecular mass of 71 kDa. The N-terminal amino acid sequence of Lac 1 was highly similar to those of laccases of some other white-rot basidiomycetes. Lac 1 showed the typical absorption spectrum of a copper-containing enzyme. The enzyme was stable in a wide pH range (4.0 to 10.0), and lost no activity up to 60 °C for 60 min. The optimal pH of the enzyme activity varied among substrates. The K(m) values of Lac 1 toward 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 2,6-dimethoxyphenol, guaiacol, catechol, and 3,4-dihydroxy-L-phenylalanine were 0.0137 mM, 0.608 mM, 0.531 mM, 2.51 mM, and 0.149 mM respectively. Lac 1 activity was remarkably inhibited by the chloride ion, in a reversible manner. Lac 1 activity was also inhibited by thiol compounds.
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa, Japan.
authors.forename: Thitinard
authors.initials: T
authors.lastname: Nitheranont
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Asada
mesh_terms: D000595:Amino Acid Sequence; D052160:Benzothiazoles / Q000378:metabolism; D002396:Catechols / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D003300:Copper / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D048691:Grifola / Q000201:enzymology*; D006139:Guaiacol / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D042845:Laccase / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000302:isolation & purification; D008031:Lignin / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011748:Pyrogallol / Q000031:analogs & derivatives / Q000378:metabolism; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D013451:Sulfonic Acids / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; D002396:Catechols; D002712:Chlorides; D005656:Fungal Proteins; D013438:Sulfhydryl Compounds; D013451:Sulfonic Acids; D011748:Pyrogallol; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C010120:pyrogallol 1,3-dimethyl ether; D006139:Guaiacol; D003300:Copper; D008031:Lignin; D042845:Laccase; C034221:catechol; D004298:Dopamine